There's a LONG list of things that affect the way a car sounds.
There are plenty of awesome sounding 6 and 4 cylinder motors and even an oddball 5 in there from time to time. One of my favorite exhaust tones for a long time has been from the Subaru boxer motors.There's also some really high revving low displacement motors like the former Toyota 4AGE Formula Atlantic motors. They could wind out to something like 12k rpm.
Each motor has it's own unique tone and whether or not you care for that tone is up to you.
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